Latest PST -80mm mod- Stage 1

[Merlin66]

I've started a new thread to show the PST mods done to a Meade 90mm f8.8 scope and a PST.

The images show the donor tube, which had to be cut by 25mm to bring the PST etalon to the correct spacing from the objective.

-The focusing tube also had to be cut... it hit an internal baffle...

The Baader 90mm ERF was used and mounted in a Body Shop cream container. The 2" nosepiece came from Teleskop-Austria.

Total time to do the mod, including removal of the gold tube from the PST body - 2hrs!

I'll document in more detail and make it available in the write -up. ( Drop me an email for a copy)

Ken

[Merlin66]

And some more images.

First light this morning clearly shows the dramatic improvement over the original PST. Surface detail and proms stand out with clarity. No sweet spot but the BF5 limits the field of view. Best with a 10.5mm eyepiece.

I'll do some checks of the variation of the etalon distance inside focus v's the final focus position. It seems that the -200mm brings the final focus close to the mid-travel of the PST knob.

Any questions just drop me a PM or email.

( Need to get some more cork strip to fix up the OTA mounting rings!!)

Ken

[Merlin66]

Managed to get a few fleeting glances at the Sun late this afternoon. I was hoping to do some images at varying etalon positions to verify the "sweet spot" issues....

No such luck, I was still looking at some interesting proms as it started to rain above me....

I didn't realise how spoiled I am with the BF15 on the SM60... really going back to using the BF5 is like looking down the centre of a toilet roll!!!

I think this latest PST etalon is a keeper! Much better than some of the previous ones... the surface clarity is as good as my SM60..

No more "mods" for me at the moment... I'm off to Oz tomorrow to see what the kids have been doing with my money....

Ken

[Psychobilly]

Safe Trip Ken...

Peter...

[Peter Drew]

Safe journey from me as well Ken, at least the internet will keep us all in touch.

[NickH]

Nice one Ken...and agree on the BF5...a bog roll is a good analogy... BF10 is the minimum ....is that etalon on a par with "others" you have seen

[David Galvin]

Safe journey Ken, keep posting when you can.

[GazOC]

Great thread Ken. This is the same mod as I hope to be doing in the next couple of weeks.

(Can't see me getting the job down to anywhere near 2hrs though..)

[Merlin66]

Thanks guys!

Nick,

The etalon on this build is certainly "crisper" than the usual run of the mill ones I've previously used. I'll do some testing when I get back and run the SM60 single and double stacked against it for comparison. I'm sure the images will show the good performance.

Ken